The role of protein in an athlete’s diet has been established since the time of the Olympic Games in ancient Greece.

The ability and level of adaptation to training is a genetically determined factor . The type of training, the duration, the intensity, the volume have a great impact on protein metabolism and on how the body responds to physical exercise.

Nutrition can influence exercise adaptations not only over the long term, but also after each individual session . Are you curious to know more details? Read more in this article.

Exercise adaptations require a series of “stress” signals at the molecular level involving:

• neuronal activations
• Mechanical changes
• Hormonal adjustments
• Metabolic changes

Protein metabolism and physical activity are related.

Proteins and protein metabolism

Physical exercise has the effect of both increasing protein synthesis, but also degrading muscle protein.

Between the two, the synthesis process is the prevailing one if after strength or resistance training the right proteins are supplied (from protein supplements or food sources) to support protein metabolism and metabolic and physiological adaptations.

Physiological adaptations due to nutrition

For proteins to increase, it is necessary that the protein synthesis capacity increase and/or the degradation capacity of a given protein decrease.

Training and diet influence the protein balance positively or negatively at every single session.

Role of proteins in muscular resistance training

Muscular resistance training has as physiological adaptations the increase of muscle cross-sectional area (hypertrophy) and a neuronal modification of muscle fiber recruitment. These adaptations to resistance exercise are mostly mechanical.

Hypertrophy can occur in two ways: by increasing the number of nuclei within each muscle fiber or by increasing the number of fibers that are recruited during exercise.

Depending on the type and intensity of your resistance training and the length of your recovery times during training you may experience one type of exercise adaptation rather than another.

Exercise increases net muscle protein synthesis if protein and energy intake are adequate. The increase in protein synthesis (the anabolic window) can last up to 2/3 days after the training session.

Protein metabolism responds to exercise differently depending on the type of protein being used.

Recent studies have investigated the impact that different sources have on this mechanism.

From what has emerged it seems that proteins of animal origin ingested after strength training produce a greater response than proteins of vegetable origin. It also appears that there is no difference between using whey protein versus casein on increased strength, power, agility.

In Search of the Holy Grail: How Much Protein?

How much protein to ingest after a training session is the crucial question for sportsmen.

Many athletes believe that a large protein intake is required to build muscle and strength. Strength athletes have a habit of consuming as much protein as possible (2.0-3.4g/kg of protein per day).

However, there is a limit to how much protein can be used by the “muscle system” to maximize protein synthesis.

Several studies report that ingesting 20-25g of protein after intense resistance exercise is sufficient to support the resulting muscle anabolism.

The American College of Sport Medicine and the American Dietetic Association and the Dietitians Association of Canada agree that the daily protein quota to support protein metabolism is equal to 1.4-1.7g/kg of protein per day.

What protein sources?

On which are the best protein sources, there is no scientific evidence that attests the superiority of proteins derived from foods or supplements.

The time an athlete has available between one commitment and another, his appetite, the possibility of sitting down to eat determine his food choices.

What is important is that a food is palatable, digestible, that it does not create gastrointestinal disturbances, that it is a ready source of macronutrients.

Proteins from supplements (in the form of powders, drinks or bars) or from food are two valid solutions determined by the functionality and by the contingent moment of the meal.

The choice is entirely personal.

Watch out for carbohydrates

One factor to consider is that some athletes replace all or part of the intake of carbohydrates and/or fats, especially carbohydrates, to promote protein intake.

This could invalidate the adaptation to training due to the lack or being underrepresented and insufficient of the main source to support physical exercise: carbohydrates.